We use the anti-\(k_t\)  algorithm with our choice of parameters for
defining jets, and employ the flavour-\(k_t\)  algorithm from
[1]} (BSZ) to assign the flavour channels. However, the BSZ algorithm is not immediately applicable here, due
to the non-global structure of the angularities. In particular, at
any perturbative order there exist contributions with only a single
jet constituent, such that the angularity variable equals zero. In
principle we need to perform the resummation around multi-jet
configurations. However, to achieve our target accuracy, it is
sufficient to guarantee that configurations occuring at LO are
dressed with the proper LL Sudakov factor. An explicit example is
given in Fig. REF (b).
Our matching scheme achieves this by
multiplying these \(Z+jj\)  events with the full NLL \(\Sigma ^\delta _\text{res}\) 
corresponding to the channel \(\delta \)  obtained after
dropping the second jet, which will contain the correct LL factor.
It is hence crucial that the flavour channel of those contributions is defined by
the single object inside the leading jet alone. At the same time, in the
example shown in Fig. REF (a), the quarks need to be
clustered in the collinear limit and the jet identified as a gluon jet. While
at this stage we could just use the combined flavour of all anti-\(k_t\)  jet
constituents, NLO contributions would spoil the IR safety of this
procedure. Examples of relevant configurations are given in
Fig. REF (c) and (d), where an IR-safe algorithm needs to
ensure that the \(g\rightarrow q\bar{q}\)  splitting is undone first in the soft gluon
limit. Here we propose and employ the following algorithm to assign flavour to
the leading anti-\(k_t\)  jet:
